| Catalytic cracking is one of very important processes of petroleum refining,because many kinds of chemicals come from it. And catalytic cracking catalyst play a key role in catalytic cracking or FCC(Fluid Catalytic Cracking). So it is necessary to develop various modified zeolites, which are main components of catalyst, in order to meet the need of diversification. And any insignificant enhancement will bring out significant profits, owing the enormous amount of process.In this dissertation, The ZSM-5 zeolites modified by phosphorus , titanium, zinc respectively, and the ReY zeolite modified by phosphorus were prepared through ion-exchange or impregnant and then being calcined by high temperature steam. The above modified zeolites' relative crystallinity, unit cell parameters, BET surface area , pore structure, collapse temperature were measured by XRD, static nitrogen volumetric adsorption method under low temperature, DTA. And their feature were observed by SEM. The catalytic performances of the modified zeolites were evaluated by heavy oil fixed bed microreactor or fluid bed microreactor.It was discovered that : (1) the ZSM-5 zeolite with lower ratio of Si to Al has better catalytic cracking performances; (2) The physiochemical properties and catalytic performances of the phosphorus-containing ZSM-5 zeolite were greatly improved, especially its activity and selectivity to propylene were drastically enhanced; (3) the titanium-containing and zinc-containing ZSM-5 zeolites can decrease the content of olefin and increase the content of the aroma to some extent in gasoline, while the selectivity to coke will become bad. But there are some differences between them; (4) the ReY modified by phosphorus has higher activity and hydrogentransfer ability, therefore it can decrease the content of olefin in gasoline and has good selectivity to coke during the course of catalytic cracking process.The above results are very useful to develop some novel catalysts.
|
PDF Full Text Request